MCQ
If $A=\left[\begin{array}{rr}2 & 1 \\ -1 & 2\end{array}\right], B=\left[\begin{array}{rr}1 & -2 \\ 2 & 1\end{array}\right], C=\left[\begin{array}{rr}1 & -3 \\ 2 & 1\end{array}\right]$,then
  • $\begin{array}{l}A+B=B+A \text { and } A+(B+C)=(A+B)+C\end{array}$
  • B
    $A+B=B+A$ and $A C=B C$
  • C
    $A+B=B+A$ and $A B=B C$
  • D
    $A C=B C$ and $A=B C$

Answer

Correct option: A.
$\begin{array}{l}A+B=B+A \text { and } A+(B+C)=(A+B)+C\end{array}$
(a) : In option (a), there are two laws, commutative law and associative law, which are satisfied by all matrices. Thus, option (a) is correct.

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